Bay Snook (Petenia splendida)

Choose a bay snook only if you can house a giant predator

The Bay Snook, Petenia splendida, is a large, fish-eating cichlid from Central America and the only species in its genus (Wikispecies). It is also sold as the Red Bay Snook; FishBase lists giant cichlid and tenguayaca as further names, and Mexican researchers call it tenhuayaca. It belongs to the cichlid family, Cichlidae, and to the tribe Heroini, the group of Central American cichlids that also includes the jaguar and wolf cichlids.

In the wild it lives on the Atlantic slope of Mexico, from the Grijalva to the Usumacinta river basins, in the Usumacinta in Guatemala, and in Belize. FishBase describes its habitat as lakes and lower river valleys, where it prefers slow water in the lower and middle reaches of rivers over soft sand or mud. It is fished commercially, farmed for food in south-eastern Mexico, and assessed as Least Concern on the IUCN Red List.

Its most remarkable feature is its mouth. The jaws shoot far forward to grab prey: in a study of jaw mechanics in Neotropical cichlids, Waltzek and Wainwright (2003) classed the bay snook as an extreme jaw protruder, with protrusion of more than 30% of head length, and found that it closed on prey faster than the oscar because its jaws reach further. They suggest this helps it catch evasive fish.

Decide from the complete care picture

Browse our South American cichlids and the American cichlids directory, or see the Central American cichlids page for its closest relatives. If you want one large fish as the focus of the room, our centrepiece fish selection shows other options.

Know what arrives and how it changes

One purchase quantity supplies one live Bay Snook, sold as a young fish. No dispatch size is listed, so ask us if you need the current size before ordering. Sex is not specified, because young fish cannot be sexed reliably.

Expect colour and shape to change as it grows

• Colour forms: our photographs show an olive-gold fish with a row of dark blotches along the side. Wikipedia’s summary describes colour from pale pink to deep red to gold, and Practical Fishkeeping notes at least two colour forms, including a pinky-gold one, and a fish that doubled in size and turned peachy.
• Sex differences: adult males are slightly larger and more intensely red; females are rounder.
• Growth: a young fish changes shape and colour as it grows, so the individual you receive will not look exactly like the gallery.

Red Bay Snook is a trade name for the red and pink colour forms; they are the same species as the olive-gold fish. The photographs show the species, not the individual you will receive.

Plan the aquarium for a fish of 30 cm and more

Sources give different adult sizes, so plan for the large end. FishBase records a maximum of 50 cm standard length (the body without the tail). Practical Fishkeeping gives up to 45 cm and several kilograms in the wild, and at least 30 cm, probably more, in aquariums. Researchers at the Universidad Juárez Autónoma de Tabasco report fish of up to 40 cm and 1,500 g in local markets.

Practical Fishkeeping recommends an aquarium of at least 180 × 45 × 45 cm for an adult, and OATA’s American cichlid care sheet sets a minimum of 300 litres for species over 15 cm. A 180 × 45 × 45 cm tank holds about 365 litres before sand and rock go in (180 × 45 × 45 = 364,500 cm³), so it meets both; more front-to-back depth gives a fish of this bulk more room to turn.

Run a three-step space check

1. Measure the base: at least 180 cm long and 45 cm from front to back.
2. Plan for the adult: a body of 30 cm or more, not the size you receive.
3. Count every other large fish as an adult too: each needs its own space and adds to the filter load.

Have the final aquarium ready, or a firm plan for it, before buying a young fish. Our tank volume calculator works out the real litres of your aquarium.

Build a strong, simple layout

Practical Fishkeeping advises heavy rocks and bogwood, so the fish cannot rearrange the décor too much. OATA suggests fine gravel or sand for American cichlids, because many species dig, with wood, rockwork or caves for cover and open space for swimming. Live plants may be dug up or eaten; plastic plants are an alternative.

Divide the footprint by function

Keep equipment robust: a large cichlid can knock loose heaters, pipework and thermometers, so fix them firmly or fit guards. OATA notes that American cichlids need a heater all year. Place the aquarium away from draughts, radiators and direct sunlight, with overhead lighting for a regular day and night.

Match warm, hard water

FishBase gives 26–30°C, pH 7.0–7.5 and hardness from 15 °dH for this species, and Practical Fishkeeping describes it as adaptable to most conditions, with pH 7.0–7.5 and general hardness above 15 ideal. OATA’s group care sheet for American cichlids gives 22–27°C, pH 6.5–8.0 and 4–12 °dH; for this species, follow the species-level values.

Use one table for habitat and waste readings

UK tap water varies from soft to very hard by region. Hard-water areas often match these values with little adjustment, while soft-water areas may need buffering. Measure your tap water and compare it in our water matcher; our aquarium water parameters guide explains general and carbonate hardness. Change conditions gradually rather than chasing a number.

Filter the aquarium for a heavy feeder

Practical Fishkeeping calls for a very powerful filter. A fish that eats whole frozen fish and large pellets produces a lot of waste, and that waste becomes ammonia, which filter bacteria turn into nitrite and then nitrate. Our aquarium filtration guide explains how to size and combine filters; for a tank of this size, two large external filters or a sump are common choices.

Follow a weekly maintenance sequence

1. Test ammonia, nitrite, nitrate, pH and hardness; OATA advises testing at least weekly.
2. Change at least 25% of the water every week (OATA).
3. Treat new water with a tap water conditioner and match its temperature to the aquarium.
4. Siphon waste and food remains from the sand.
5. Check filter flow, and rinse media lightly in removed aquarium water, never under the tap.

Mature the filter before the fish arrives; our nitrogen cycle guide explains fishless cycling. Remove any food the fish ignores within a few minutes, because large meaty leftovers foul the water quickly.

Feed meaty foods in measured meals

In the wild the bay snook feeds on fish; FishBase gives it a trophic level of 4.5, the level of a top predator. In aquariums, Practical Fishkeeping notes, it takes most meaty frozen foods and pellets. OATA recommends cichlid pellets or granules as the base diet for American cichlids, with foods such as cockles, lance fish and prawns for larger species, fed once a day in amounts eaten within a few minutes.

Build a varied menu

• Staple: large cichlid pellets or sticks.
• Frozen variety: Cichlid Mix frozen food, Cockle Meat, Mussel Meat and Large Krill.
• Whole frozen fish: thawed Smelts suit a fish-eater; cut them to size for a young fish.
• Feeding tongs: the jaws strike fast, so keep fingers out of the water at feeding time.

We do not recommend live feeder fish: frozen foods avoid carrying disease from another tank and are easier to measure. Do not overfeed either, because large cichlids are greedy and put on fat easily.

Introduce it and watch the first weeks

Before the fish arrives, confirm that ammonia and nitrite are zero, the temperature is in range and the aquarium is the size the adult will need. Add it to a quiet aquarium and keep the lights low on the first day.

Use the floating-bag method

1. Switch off the aquarium lights and float the sealed bag for 10 minutes so the temperatures equalise.
2. Add small amounts of aquarium water to the bag over up to 20 minutes.
3. Release the fish, letting as little bag water as possible into the aquarium.
4. Dispose of the bag and its water appropriately.
5. Watch the fish closely for the first week, especially the water quality.

These are OATA’s steps; our guide to acclimatising new fish explains them in more detail. A young fish may hide for a few days. Offer a small meal of frozen food the following day, and retest ammonia and nitrite after the addition. Our delivery information covers delivery days and the Live Arrival Guarantee.

Watch health and behaviour

OATA describes healthy fish as having clear, bright eyes, undamaged fins, intact scales, no ulcers or bumps, normal swimming and steady breathing. Note how your fish behaves once it has settled, so that changes stand out.

Pair each observation with an action

Do not diagnose from a single sign. If a problem continues after the water checks, contact us with the aquarium size, temperature, pH, hardness, ammonia, nitrite and nitrate readings, the tank mates and what you have seen.

Plan tank mates around its mouth

Any fish small enough to fit in its mouth will be eaten, and the bay snook’s mouth opens far wider than it looks when closed. OATA advises keeping the more aggressive American cichlids alone or only with equally aggressive cichlids, and that is the safest plan here. None of the sources we checked lists proven tank mates for this species, so treat every companion as a trial, keep a spare aquarium available and never add a fish it could swallow.

Use a suits and avoid list

Our tank mate checker screens proposed companions. For care on the same scale, compare the Jaguar Cichlid and the Motaguense Cichlid, or read our cichlid care guide, Jack Dempsey guide and Oscar guide for large-cichlid tank planning.

Understand breeding before you buy a pair

Like other American cichlids, the bay snook lays eggs and guards its young: OATA’s group care sheet notes that these cichlids clean a flat surface before spawning, guard the fry until they swim freely and become aggressive while breeding. In aquaculture research at the Universidad Juárez Autónoma de Tabasco, broodstock spawned naturally; the newly hatched young were collected from the nests and became free-swimming about six days after fertilisation, at around 28°C and pH 7.3. The larvae did not readily accept artificial food at first and were raised on newly hatched brine shrimp (Artemia) nauplii.

What breeding means at home

• A pair can only be chosen from mature fish, because young fish cannot be sexed reliably.
• Breeding cichlids are aggressive, so OATA recommends a dedicated set-up; for this species that means a very large aquarium.
• Fry need live first foods such as newly hatched brine shrimp, then larger foods as they grow.
• A spawn produces many young predators: plan homes for them before you start.

Answer Bay Snook buying questions

What is a Bay Snook?

Petenia splendida, a large, fish-eating cichlid from Mexico, Guatemala and Belize, and the only species in its genus. It is also sold as the Red Bay Snook and is known in Mexico as tenhuayaca.

How big does a Bay Snook get?

FishBase records up to 50 cm standard length in the wild. Practical Fishkeeping expects aquarium fish to reach at least 30 cm, and probably more.

What size tank does a Bay Snook need?

At least 180 × 45 × 45 cm for an adult (Practical Fishkeeping), about 365 litres, with very powerful filtration. OATA’s minimum for American cichlids over 15 cm is 300 litres.

Can a Bay Snook live with smaller fish?

No. It eats fish, and its jaws shoot forward to catch anything that fits in its mouth. Keep it alone or with robust fish of a similar size in a very large aquarium.

What water does a Bay Snook need?

Warm, hard water: FishBase gives 26–30°C, pH 7.0–7.5 and hardness from 15 °dH. Keep ammonia and nitrite at zero and nitrate low.

What does a Bay Snook eat?

Meaty frozen foods such as cockle, mussel, krill and whole smelts, plus large cichlid pellets, once a day in amounts eaten within a few minutes.

Is the Red Bay Snook a different fish?

No. Red Bay Snook is a trade name for the red and pink colour forms of the same species. Colour ranges from olive-gold to pink, red and gold.

Can I tell male and female Bay Snook apart?

Not reliably in young fish. Adult males grow slightly larger and more intensely red, and females are rounder.

Consult the care references

• FishBase: Petenia splendida — names, distribution, habitat, maximum size, water values, diet and fisheries.
• Practical Fishkeeping: Petenia splendida, the bay snook cichlid — wild and aquarium size, colour forms, tank size, décor, water and feeding.
• Wikipedia: Petenia splendida — colour range, sex differences, jaw and diet summary.
• Wikispecies: Petenia — the genus and its single species.
• Waltzek & Wainwright (2003), Functional morphology of extreme jaw protrusion in Neotropical cichlids, Journal of Morphology 257: 96–106 — jaw protrusion and prey capture.
• Vidal-López et al. (2009), Hidrobiológica 19(3): 211–216 — farmed tenhuayaca in Tabasco: size in local markets, natural spawning and larval rearing.
• OATA: How to look after American cichlids — group tank size, water quality limits, feeding, maintenance, compatibility and acclimatisation.